The invasion of kitchen ants seemed inevitable … until the winter ant came along

Argentine ants
CC BY 2.0 Matthew Townsend/flickr

Argentine ants like those in your kitchen are ruthless invaders, hungrily vying for world domination, but they may have met their match in the form of the winter ant.

In the 1890s something happened in the United States that would have a profound and enduring impact on the future of the country. Sneaking passage on Brazilian coffee ships docked in New Orleans, the Argentine ant (Linepithema humile) made landfall on the nation’s shores … and they’ve been taking over ever since. If you’ve got ants at your picnic, in your garden, doing ninja moves in your kitchen, they are likely Argentines, known for their straight-line marching and extraordinary perseverance.

Most ants are pugnacious by nature, if you combine ants from different colonies they will fight until death, even if they’re the same species. But Argentines have a unique secret pact; they don’t fight with other members of their species. So while other ants are keeping their numbers down with ant-style civil wars, Argentine ants are essentially building a huge world colony. They've been called “the most populous known animal society," with trillions upon trillions of members, dwarfing the human population by leaps and bounds. And they are brutal, and they are wiping out other species everywhere.

As Elliott Kennerson writes for KQED Science:

For about 200 years, the Argentine ant expansion story has been the slow-moving train wreck of myrmecology, the study of ants. From remote origins in the Paraná River valley in Paraguay and Argentina, this virulent invasive species has moved out to claim much of the world’s most desirable territory, whether you’re an ant or a human.

Wherever they go, Argentine ants eliminate the competition – mostly other ants, but sometimes bees, termites and ladybugs – with a take-no-prisoners approach. Invade, dismember, consume. Repeat. Resistance is futile. The basic wisdom among ant scientists is that if you see Argentines, it’s already too late.

As anyone battling this indefatigable invader on the homefront knows, these guys don’t give up. Battling them often seems a losing proposition, even when it’s giant human versus tiny ant.

Scientists have mostly seemed convinced that not much could stop the forward march, but that was before Jasper Ridge. The 1,200-acre preserve belonging to Stanford University in California is home to the winter ant, which might just be the secret weapon against the Argentine marauder. Deborah Gordon is a professor of biology who studies ants at Stanford University; she began tracking the first Argentine interlopers into Jasper Ridge in 1993. Anticipating a massacre of local ants, she instead discovered the perseverance of another species, the winter ant, and its novel defensive strategy … which seems to offer hope that mega-domination by the Argentine ant can be halted, and even reversed.

It’s a great story, and is wonderfully told in this video by Deep Look, the always-awesome collaboration between KQED San Francisco and PBS Digital Studios. See the Argentines and their foes in very close-up action; it's better than Hollywood!

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